Typically, it is desirable to activate dopants in semiconductors in a manner that does not allow the dopants to diffuse during activation. High temperature annealing technologies have been created with faster dwell times to allow dopant activation with minimal thermal diffusion. Faster dwell times minimize the amount of time that the high temperatures must be sustained to activate the dopants. Examples of conventional high temperature anneals that implement fast dwell times are laser spike annealing, milli-second annealing, and rapid thermal annealing. Even though fast dwell times are used to prevent the dopants from diffusing, the high temperatures required by the conventional high temperature anneals still may exceed 1000 degrees C., and these high temperatures are often times not tolerable even for fast dwell times. To continue Moore's law scaling, devices and device structures are being introduced with reduced thermal tolerances, and thermal budgets are being reduced for semiconductor processing systems. For example, thermal tolerances for some semiconductor substrates during annealing have been reduced to below 400 degrees C.
It is becoming common wisdom to use conventional electromagnetic (EM) wave treatments in thermal annealing and dopant activation processes. Conventional EM wave treatment heats the dopants locally, which then reduces the heat that the substrate as a whole receives. The heating that the substrate is exposed to comes from residual heating which requires reduced temperatures below 500 degrees C. However, conventional EM wave treatment with reduced temperatures below 500 degrees C. still precludes applications that require temperatures to be reduced even further.
Conventional EM wave treatment typically implements surface waves that resonate across the surfaces of the semiconductors at EM wave frequencies where the surface waves are conventional standing waves. Conventional EM wave treatments implementing conventional standing waves are inefficient, non-uniform, and difficult to control, which has the effect of increasing the temperatures of the conventional EM wave treatments rather than lowering the temperatures. Means to implement EM wave treatments of semiconductor surfaces with lower processing temperatures has been implemented by unloading the EM wave in a resistive load. However, the cost of microwave generation is still substantial even with lower processing temperatures. In addition, cooling of the resistive load is an involved process. There is a need for a system that reduces the cost of microwave generation and eliminates the complexity of the resistive load cooling.